A woman in agony of spirit might turn her head just so; a man in deep humiliation probably would wring his hands in such a way. From straws like these, drawn from completely different sources, the fabric of a character may be built.
An actor rides in a bus or railroad train; he sees a movement and applies it to a new role. The whole garment in which the actor hides himself is made of small externals of observation fitted to his conception of a role.